We propose to test the efficacy of an after school dance program to reduce weight gain and risk for type 2 diabetes in a sample of predominantly Latina, Pacific Islander, Filipina and African-American pre-adolescent girls. Over the past two decades we have witnessed an emerging epidemic of type 2 diabetes in children, adolescents and young adults. The rise in type 2 diabetes has been attributed, in large part, to the accompanying epidemic of obesity. Girls and children of non-European ancestry are at highest risk for pediatric type 2 diabetes. After school dance programs may be a generalizable environmental strategy to promote long-term moderate-to vigorous physical activity among girls. Two pilot studies of dance in predominantly low-income African-American and Latina samples confirmed that (1) dance is a highly attractive and feasible form of activity for preadolescent girls and (2) a dance intervention can result in reduced body mass index (BMI) and increased fitness among girls. We propose a 2-year randomized, controlled trial involving 240 2nd, 3rd and 4th grade girls and their families, from low-income, ethnically diverse elementary schools. Girls will be randomized to the after school dance intervention or a non-specific "active placebo" control group. Dance classes will be conducted at their school sites. Both social and performance dance will be taught, emphasizing ethnic dance styles and traditions. In-home/school-based measures of height, weight, waist circumference, triceps skinfold thickness, blood pressure, resting heart rate, and self-reports of physical activity and sedentary behaviors will be collected every six months and fasting insulin, glucose, and lipoprotein levels, and four days of physical activity monitoring and three 24-hour dietary recalls will be obtained annually. We will use random regression models to test the following primary hypothesis: Compared to controls, girls in the dance intervention treatment group will significantly reduce their weight gain over a 2-year study period. Body mass index (BMI, kg/m2) will be the primary measure of body fatness. Secondary outcomes include fasting insulin, fasting lipoproteins, blood pressure and resting heart rate, physical activity levels, and dietary calorie and fat intake. We will also perform baseline and prospective risk factor/targeting studies and process studies, to better understand the relevance of the results and the intervention.